.TH std::generate_canonical 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::generate_canonical \- std::generate_canonical

.SH Synopsis
   Defined in header <random>
   template< class RealType, std::size_t Bits, class Generator >  \fI(since C++11)\fP
   RealType generate_canonical( Generator& g );

   Generates a random floating point number in range [0, 1).

   To generate enough entropy, generate_canonical() will call g() exactly \\(\\small k\\)k
   times, where \\(\\small k = \\max(1, \\lceil \\frac{b}{\\log_2 R} \\rceil)\\)k = max(1, ⌈ b
   / log
   2 R ⌉) and

     * b = std::min(Bits, std::size_t {std::numeric_limits<RealType>::digits}),
     * R = g.max() - g.min() + 1.

.SH Parameters

   g - generator to use to acquire entropy

.SH Return value

   Floating point value in range [0, 1).

.SH Exceptions

   None except from those thrown by g.

.SH Notes

   Some existing implementations have a bug where they may occasionally return 1.0 if
   RealType is float GCC #63176 LLVM #18767 MSVC STL #1074. This is LWG issue 2524.

.SH Example

   Produce random numbers with 10 bits of randomness: this may produce only k * R
   distinct values.


// Run this code

 #include <iostream>
 #include <random>

 int main()
 {
     std::random_device rd;
     std::mt19937 gen(rd());
     for (int n = 0; n < 10; ++n)
         std::cout << std::generate_canonical<double, 10>(gen) << ' ';
     std::cout << '\\n';
 }

.SH Possible output:

 0.208143 0.824147 0.0278604 0.343183 0.0173263 0.864057 0.647037 0.539467 0.0583497 0.609219

.SH See also

   uniform_real_distribution produces real values evenly distributed across a range
   \fI(C++11)\fP                   \fI(class template)\fP
